ABSTRACT
The improvement of the combustion properties of coal and biomass by blending and carbonization was investigated. Proximate and ultimate analysis of coal, sawdust, corn cob and their blends were carried out using ASTM methods. The proximate and ultimate analyses were repeated on the five blends after carbonization at 500oC for one hour. Ten mixtures of coal-sawdust and coal-corn cob blends were made into briquettes using starch binder. The calorific values of the samples were determined using a bomb calorimeter, while the thermal efficiency of the briquettes was obtained using the water boiling test analysis. Pollution potential of the fuel samples were derived using a hypothetical power plant simulation. The quantity of CO2, NO2 and SO2 that would be emitted per hour in a 20MW power plant were calculated. The result of the proximate analysis of the raw samples (coal, sawdust and corn cob) showed that coal had the highest fixed carbon (42.38%) and the lowest moisture content (4.28%). Sawdust had the lowest fixed carbon (12.35%) while corn cob had a fixed carbon content of 15.65%. The results obtained showed considerable correlation between the uncarbonized coal-sawdust and coal-corn cob blends. The carbonized blends of both the coal-sawdust and coal-corn cob blends showed an improved fixed carbon content and volatile matter, relative to the uncarbonized. The calorific values and other fuel properties were of similar trends. The results of the ultimate analysis for coal were 70.04% carbon, 5.32% hydrogen, 2.03% nitrogen and 1.02% sulphur. Corn cob had 48% carbon, 5.79% hydrogen and 0.89% nitrogen while sawdust had 48.78% carbon, 5.79% hydrogen and 0.89% nitrogen. Corn cob and sawdust had no sulphur content, while the uncarbonized coal-sawdust and coal-corn cob blends showed decreasing carbon content. This study revealed that the fuel properties of coal and biomass can be improved by blending and carbonization. The simulated power plant analysis of the fuel showed that blending of coal with biomass reduced the SO2 and NO2 emissions to an extent. For NO2, the value of coal-sawdust blends ranged from 82.8-190.8 kg/hr, reduced from 198 kg/hr in coal, while the SO2 content was reduced from 60.5 kg/hr in coal to 5.6 – 50.4 kg/hr in different blends. Therefore, blending of coal with either sawdust or corn cob should be encouraged in coal fired power plants to reduce environmental pollution.
TABLE OF CONTENTS
Page
TITLE PAGE……………………………………………………………………………. i
CERTIFICATION………………………………………………………………………… ii
DEDICATION…………………………………………………………………….……… iii
ACKNOWLEDGEMENTS……………………………………………………….……… iv
ABSTRACT……………………………………………………………………….……… v
TABLE OF CONTENTS ………………………………………………………….……… vi
LIST OF FIGURES ………………………………………………………………………. ix
LIST OF TABLES…………………………………………………..……………… x
ABBREVIATIONS………………………………………………………………….……… xi
CHAPTER ONE
INTRODUCTION
1.1 Introduction………………………………………………………………… 1
1.2 Energy and its uses………………………………………………………… 2
1.2.1 Electricity generation……………………………………………………… 2
1.2.2 Transportation……………………………………………………………… 2
1.2.3 Industrial sector…………………………………………………………… 2
1.2.4 Domestic use……………………………………………………………… 3
1.3 Renewable and non-renewable energy sources…………………………… 3
1.3.1 Renewable energy sources………………………………………………… 3
1.3.1.1 Biomass energy…………………………………………………………… 3
1.3.1.2 Solar energy……………………………………………………………… 4
1.3.1.3 Wind energy……………………………………………………………… 4
1.3.2 Non-renewable energy sources…………………………………………… 4
1.3.2.1 Coal ………………………………………………………………..……… 4
1.3.2.2 Petroleum…………………………………………………………….…… 4
1.4 Energy Resources in Nigeria……………………………………………… 4
1.4.1 Coal and biomass in Nigeria……………………………………………… 5
1.5 Energy crises and Environmental problems…………………………… 6
1.5.1 Biomass and climate change…………………………………………… 7
1.6 Justification of the study………………………………………………… 8
1.7 Objectives of the study…………………………………………………… 9
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 Origin and formation of coal…………………………………………… 10
2.1.1 Classification of coal………………………………………………… 11
2.2 Coal development in Nigeria……………………………………… 11
2.2.1 Coal reserves and mining in Nigeria………………………………… 12
2.2.1.1 Surface mining……………………………………………………… 12
2.2.1.2 Underground mining………………………………………………… 13
2.2.2 Coal mining and environmental degradation………………………… 13
2.3 Composition of coal………………………………………………… 13
2.3.1 Proximate analysis of coal………………………………………………… 13
2.3.2 Ultimate analysis of coal…………………………………………………… 14
2.4 Coal utilization………………………………………………………… 14
2.4.1 Electric power generation……………………………………………… 14
2.4.2 Domestic heating……………………………………………..……… 15
2.4.3 Iron and steel…………………………………………………………… 15
2.4.4 Environmental pollution from coal use………………………………… 15
2.5 Biomass as an alternative energy resource……………………………… 16
2.5.1 Biomass energy resources……………………………………………… 17
2.5.2 Classification and types of biomass resources…………………………… 18
2.5.3 Analysis of biomass……………………………………………………… 19
2.6 Sawdust and corn cob as energy sources……………………………… 19
2.6.1 Sawdust…………………………………………………………….……… 20
2.6.2 Corn-cob………………………………………………………………… 21
2.6.3 Environmental and disposal problem of sawdust and corn cob…..……… 22
2.7 Biomass development and use in Nigeria and other African countries… 22
2.8 Co-generation of coal and biomass……………………………………… 24
2.9 Briquetting of solid fuels………………………………………………… 24
2.9.1 Briquetting of saw dust and corn cob…………………………………….…25
2.9.2 Physico-chemical and combustion characteristics of sawdust briquette..…25
2.9.3 Effect of binders on the performance of briquette……………..……… 26
2.10 Carbonization of coal and biomass……………………………………… 27
2.10.1 Low temperature carbonization…………………………………………… 28
CHAPTER THREE
EXPERIMENTAL
3.1 Materials and Equipment…………………………………………………… 29
3.2 Sampling and sample preparation………………………………….……… 29
3.3 Proximate analysis of samples……………………………………..……… 29
3.3.1 Determination of moisture content………………………………………… 29
3.3.2 Determination of volatile matter…………………………………………… 30
3.3.3 Determination of ash……………………………………………….……… 30
3.3.4 Determination of fixed carbon…………………………………….……… 30
3.4 Ultimate analysis of samples……………………………………………… 30
3.5 Determination of fuel ratio………………………………………..……… 30
3.6 Calorific value determination……………………………………..……… 31
3.7 Carbonization of samples………………………………………………… 31
3.8 Pollution potential simulation…………………………………………… 32
3.9 Briquetting………………………………………………………..……… 33
3.10 Determination of fuel properties of briquette…………………….……… 33
3.10.1 Water boiling test………………………………………………..……… 33
3.10.2 Ignition time……………………………………………………………… 34
3.10.3 Afterglow time…………………………………………………………… 34
CHAPTER FOUR
RESULTS AND DISCUSSION
4.1 Results………………………………………………………………….…… 35
4.2 Discussion……………………………………………………………………..39
4.3 Conclusion ……………………….………………………………………… 50
REFERENCES………………………………………………………………………… 51
APPENDICES………………………………………………………………………… 60
LIST OF FIGURES
Page
Figure 2.1: Schematic diagram showing coal formation ………………………………. 10
Figure 2.2: Organic composition of wood …………………………………………….. 21
LIST OF TABLES
Table 1: Result of the Proximate analysis and calorific values of Sub-bituminous
Coal, Sawdust, Corn cob, Coal-Sawdust blend and Coal-Corn cob blend……….. 35
Table 2: Result of the Elemental analysis of Coal, Sawdust, Corn cob, Coal-Sawdust
and Coal-Corn cob blends……………………………………………………… 36
Table 3: Result of the Elemental analysis of carbonized Coal-Sawdust and Coal-Corn
cob blends…………………………………………………………………… 36
Table 4: Result of Fuel Ratio of Coal, Corn cob, Sawdust and their carbonized and
uncarbonized blends…………………………………………………..……… 37
Table 5: Pollution potential of different Fuel Blends in kilogramme per hour………… 38
Table 6: Combustion Properties of Coal-Sawdust and Coal-Corn cob briquette……… 38
Table 7: Result of Water Boiling Test…………………………………………………. 39
ABBREVIATIONS
CS- Coal-Sawdust
CCS- Carbonized Coal-Sawdust
CC- Coal-Corn cob
CCC- Carbonized Coal-corn cob
DAF- Dry-ash free
V.M- Volatile matter
F.C- Fixed carbon
I.T- Ignition Time
A.G.T- Afterglow time
T.E- Thermal Efficiency
SD- Sawdust
COB- Corn cob
B.R- Burning Rate
S.F.C- Specific Fuel Consumption
CHAPTER ONE
INTRODUCTION
1.1General Introduction
History has revealed that many centuries ago,man made use of energy in its natural form to aid daily living. From burning wood for cooking, to utilizing the force of flowing water for irrigation and using sun light to dry and preserve foods. The use of energy has remained unabated till date, only that energy use has changed from the brute and basic methods, into more sophisticated and industrial ways.
The period from the late 1700s into early 1800s in England and Western Europe have been called the Industrial Revolution. The dawn of the Industrial Revolution paved way for an age of energy. This period witnessed drastic changes in virtually every aspect of human life. It was an advent of machines and use of mechanized methods. Ever since, man’s desire to live a better and civilized life, with the help of modern technology has caused a great demand for energy in its many forms. This also came with the adoption of lifestyles that has an increased demand for energy use.The technological advances that occurred during the industrial revolution of the 1700s have numerously been credited to coal. Before this period, wood was the major source of energy.
Consequently, the increasing adoption of a lifestyle that was energy intensive came with the quest for a better energy resource. Today, these energy needs are majorly supplied by fossil fuels such as coal, natural gas and petroleum. These fuels are known as primary energy sources, and they provide most of the energy that powers man’s modern life. Petroleum was discovered by Edwin Drake in 1859 in the United States. It was first used for lightening lamps and other basic uses. With the breakthrough of petroleum refining into various fractions, and increased use of internal combustion engines in automobiles, motor cycles and aero planes, the demand for petroleum never dwindled. In 1992, the National Energy Strategy in the United States concluded that, “for the foreseeable future, oil [Petroleum] will remain a critical fuel for the United States and all other industrialized nations.” The quest for oil has continued up to the point that it has become a potential economic and security concern for developed countries, especially after the 1970s crisis. Despite these, coal has not been totally abandoned. It is used for electricity generation in countries with large coal reserves, with no cheaper alternative. For example, 73% of South Africa’s primary energy is derived from coal1. In China’s energy strategy, coal plays the most important role especially for its electricity sector.
The availability of energy resources and its effective utilization has a bearing on national development and living standards. Energy is required for national development, and its presence directly betters the standard of living. The availability of vast amounts of energy resources in a nation is supposed to bring significant progress to the economy, and living standards of her citizenry. The effect of energy can be seen in its ability to multiply the work of a few labourers by many folds e.g an automobile would move many folds faster than man. The value of energy is noticed when its utilization results in a final product. Good management practices should aim at reducing the rate of exhaustion of the resource base, rather than increase or even sustain the rate of consumption.Consumers and manufacturers, who enjoy the efficient use of energy, should become more knowledgeable about it.
1.2 ENERGY AND ITS USES
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